Longest Time Spent on The Top 40 by a Track:
75 weeks by Frank Sinatra's "My Way" between April 1969 and Sep 1971. It has spent a further 49 weeks in the Top 75 and never bettered the number 5 slot achieved upon its first chart run.

Judy Collins' "Amazing Grace" holds the record for the single with most weeks on the chart for a female artist (42 weeks).

Frankie Goes To Hollywood's "Relax" has most weeks on the Top 40 for a track by a group (42 weeks).

Longest Continuous Run in The Top 40 by a Track:
37 weeks. This record is shared by Frankie Goes To Hollywood's "Relax" (1983/4) and Nickelback's "Rockstar" (2007/8).

Hit For Most Artists
Two tracks have become Top 40 hits for seven separate artists:

Biggest Jump
The biggest jump within the Top 40 was by Pink's "So What", leaping from no. 38 (only two days worth of downloads contributed to that postion due to an unconventional release date to the online stores) to no. 1 (w/e 11th Oct 2008). No record could match that leap in the chart's 56 year history. The previous record had been held by Embrace's single "World At Your Feet" which jumped from number 38 to number 3 in June 2006 (35 places). It resulted from the single being available purely as a download one week (at no. 38) to a 'full' release (on CD) the following week, which also coincided with the start of the World Cup (the single was the official England song for Germany 2006).

The biggest leap by a song appearing in precisely the same format(s) in successive charts is a 34 places for "You Drive Me Crazy" by Shakin' Stevens (no. 39 to no. 5 in May 1981).

Biggest jump within the Top 75 was "Come With Me" by Puff Daddy featuring Jimmy Page which leapt from no. 75 to no. 2 in Aug 1998, though this involved the conversion from imported copies to British releases.

The biggest 'authentic' jump within the Top 75 was by Steps in Jan 2001. Some stores mistakingly releasing the single a day early and it sold sufficient copies to make no. 72 in the chart. The following week it was released fully and rose to no. 2.

Shortest Chart Stay For A Number One, Two, Top Ten Hit
The shortest stay in the Top 40 by a chart-topper is just three weeks. It has happened on two occasions:

In 1997, Blur's "Beetlebum" entered the chart at the top spot. In its second week it dropped to number 7. It then descended to number 29 before vanishing altogether.

In 2005, a commemorative limited re-issue of Elvis Presley's "It's Now Or Never" entered the chart at no. 1, spending a single week there before falling to no. 14, and then to 27 before leaving the chart. (The track had, though, previously spent 19 weeks in the Top 40 in 1960/1977.)

Initially, Elvis Presley's 2005 re-issue of "Jailhouse Rock" (a limited edition of, supposedly, 27,500 copies) spent just two weeks inside the Top 40. After a single week at the top, it fell to number 10 before disappearing out of the Top 40 altogether. This, momentarily, set a new record for the shortest chart stay for a no. 1 (2 weeks) but the record company gave in to public pressure though, making extra copies available to satisfy the demand of disgruntled fans. The single consequently returned to the Top 40 as a re-entry a fortnight later. (Of course, this track had also previously spent 22 weeks inside the chart in its original form.)

Nine records tie for the shortest stay in the Top 40 for a track peaking at no. 2.
Two of them are by The Manic Street Preachers. In October 2004 their single "The Love Of Richard Nixon" entered the chart at no. 2. The following week it tumbled to no. 22 and then vanished. Then, in Jan 2005, they entered the chart at no. 2 with "Empty Souls." The following week, it dipped to no. 26, exiting the Top 40 the following week.In 1992, Shut Up And Dance's single "Raving I'm Raving" was abruptly deleted following complaints from Marc Cohn who objected to the fact that his "Walking In Memphis" track had, without his consent, been turned into a rave anthem! It, thus, had a chart run of just two weeks (no.2, no.15, out)
Elvis Presley's 2005 limited edition re-issue of "Wooden Heart" entered the chart at no. 2, falling to no. 24 the following week before dropping out of the top 40 altogether (though it had previously spent 22 weeks in the Top 40 in 1961). Within a matter of weeks, Elvis' "(You're The) Devil In Disguise (re-issue)" entered at no. 2, immediately falling to no 26 before departing the top 40 (it had spent 11 weeks inside the Top 40 in 1963). Soon after this, Elvis' "Crying In The Chapel (re-issue)" entered at no. 2, immediately falling to no 33 and then out (it had 14 weeks inside the Top 40 in 1965). Shortly afterwards, "Way Down (re-issue)" entered at no.2 falling, the following week, to number 30 and then out (though it has 11 weeks in the Top 40 in 1977).
Cliff Richard's seasonal number 2, "21st Century Christmas / Move It" exited the Top 40 naturally after a run of just two weeks, entering at no.2 before descending to no. 7 and out.
The most recent example is McFly's "One For The Radio" which entered at no. 2 in July 2008 before falling to no. 21 and then out.

Five tracks have spent a single week in the Top 10 before dropping out of the 40 altogether;

The Pet Shop Boys - "A Red Letter Day" (no. 9, 1997)

Embrace - "My Weakness Is None Of Your Business" (no. 9, 1998)

The Wedding Present - "Come Play With Me" (no. 10, 1992)

The Manic Street Preachers - Autumnsong (no. 10, 2007)

Wet Wet Wet - Weightless (no. 10, 2008).

Biggest Fall Inside The Top 40
In spring 2005, the commemorative series of limited edition singles released in honour of what would have been Elvis Presley's 70th birthday produced some unusually large chart falls. In March 2005, the re-issue of Elvis Presley's "She's Not You" entered the chart at no. 3. before following the following week to no. 36; a record-breaking 33 place tumble. This precise scenario was repeated (as part of the same series of re-issues) by "A Lttle Less Conversation" (as Elvis vs JXL) in May 2005.

Other 'magnificient' falls by the 2005 re-issued Elvis titles incuded a 32 place drop ("Return To Sender"" no. 5 to no. 37) and a 31 place decline for "Crying In The Chapel" (no. 2 to no. 33).
Prior to the series of Elvis releases, The Doves single "There Goes The Fear" held this record. It was deleted after its first day on sale. Consequently, having entered the chart at number 3, it fell to no. 34 the following week, matching Eddie's Holman's 27 year-old record for a 31-place fall ["(Hey There) Lonely Girl" fell from no. 7 to no. 38 in 1974.]

Greatest Drop Out Of The Top 40
The highest position from which a song has dropped out of the Top 40 entirely is no. 5. This happened in 2006 when "Crazy" by Gnarls Barkley was deleted by its record company whilst at number one. A new chart rule at the time stipulated that a track was permitted two weeks in the chart after deletion before being excluded. "Crazy" dropped from 1 to 2 to 5 (with a few copies still in the shop plus download sales) before its exclusion (its sales were sufficient for the track to remain in the Top 10 the following week and for a more graceful retreat all round had it not been excluded). Indeed, following a further change in chart legislation the track was re admitted to the Top 40 in Jan 2007.

The highest position from which a song has 'naturally' dropped out of the Top 40 entirely is no. 7. This happened to Cliff Richard for the double A-sided "21st Century Christmas / Move It" (w/e 6th Jan 2007.) [In fact, the song should have fallen from no. 6 if the chart rules in place at the time had been applied to the letter as "Fairytale Of New York" was no. 6 but was technically ineligible as the most recent physical format had been over 12 months previously. The rules were bent so as not to make a mockery of the chart.]

Prior to this, the highest 'exit' position had been number 9 - on four occasions: Connie Stevens' "Sixteen Reasons " (1960); David Bowie & Bing Crosby's "Peace On Earth/Little Drummer Boy" (1983); Pet Shop Boys' "A Red Letter Day" (1997); Embrace's "My Weakness Is None Of Your Business" (1998). A drop-out of the same magnitude occurred with Simon and Garfunkel's "Mrs Robinson" EP (1969) but the latter was due to the implementation of a decision to exclude EPs from the singles chart.

Back in 1953, before the chart's expansion to a Top 40, Diana Decker's "Poppa Piccolino" fell out of the chart entirely from the no. 2 position (though the third best-seller as there was a joint no. 1). However, the chart was only a top 12 in those days so this is a less sensational exit. Furthermore, the record re-entered at no. 5 the week after dropping out - thus suggesting that it was not far outside the top 12 during its week of absence.

Most Weeks On The Top 40 Without Making The Top 10
Between 19th Jan 1961 and 21st Sep 1961, "A Scottish Soldier (Green Hills Of Tyrol)" by Andy Stewart with The Michael Sammes Singers spent 36 weeks on the Top 40 and did not progress above number 19. Even more impressively, this was achieved in a single chart run (ie. no re-entries).

Nearest 'Miss'
A 2005 12" re-issue of Faithless' "Insomnia" (which due to chart rules was considered a completely separate entry to both the previous releases) managed 19 weeks in the top 75 without ever getting any higher than number 48.
In terms of an 'original' recording (ie. not a re-issue) the record is held by Ken Barrie's theme tune to the TV programme "Postman Pat." It had three separate chart runs peaking at 44, 54 and 59 respectively, spending a total of 15 weeks in the Top 75.
(Close contender to this crown was Evelyn Champagne King who spent 23 weeks on the chart but managed to climb as high as number 39, thereby just missing out on this accolade).

Making The Top 40 Without UK Release
When a potentially very popular single is on sale elsewhere in the world but is unavailable in the UK, astute distribution companies will sometimes import copies to partially fulfil customer demand. Besieged record shops are more than happy to sell these prior to the official UK release. The single may, therefore, sell in sufficient quantities to enter the chart on import sales alone. On five occasions in the history of the chart, the British public have been so eager to own a particular title that they have been prepared to pay the inflated import price and propel the single into the Top 40 without its official UK release:

Cliff Richard and the Shadows - "Gee Whiz Itís You" (made no. 4 in 1961. The single, intended purely for overseas markets, was exported in large quantities. Shrewd record retailers imported copies back into UK to satiate frustrated Cliff fans.)

The Jam - "That's Entertainment" (made no. 21 on import in 1981. It subsequently went to no. 60 and no. 57 on two domestic releases in 1983 and 1991 respectively).

Lou Bega - "Mambo No 5" (no. 31 on import; no. 1 when released domestically - both in 1999).

Eiffel 65 - "Blue (Da Be Dee)" (no. 39 on import; no. 1 when released domestically - both in 1999).